Clinical, radiographic, and scintigraphic comparison of the mechanical stability of Mueller and Zweymueller total hip prostheses

Twenty-two cemented Mueller and 25 uncemented Zweymueller total hip arthrop lasties (THAs) were performed in the same period in 47 consecutive randomly selected patients with unilateral primary osteoarthritis. Patients were ev aluated using the same clinical and radiographic protocol preoperatively; 3 , 6, and 12 months postoperatively; and annually thereafter as well as with Tc 99m MDP three-phase bone scintigraphy 3, 6, 12, and 24 months postopera tively. At 11 periprosthetic regions of interest (ROls) around the stem and socket of each prosthesis, several radiographic parameters and bone scinti gram uptake grade were recorded and correlated to determine the significanc e of early scintigraphic uptake for prediction of the stability of cemented and uncemented THA components over time. Around stable Zweymueller and Mueller sockets, the radionuclide uptake was similar during all periods of observation. Radionuclide uptake around stabl e Zweymueller stems was significantly more than around stable Mueller stems at the medial femoral cortex 3 and 6 months postoperatively, at the latera l femoral cortex 3-24 months postoperatively, and near the tip of the stem 3 months postoperatively. Radionuclide uptake around stable Mueller stems w as significantly more than around Zweymueller stems at the greater trochant er 6 and 12 months postoperatively and at the lesser trochanter 12 months p ostoperatively. Any significant deviation of radionuclide uptake at any ROI , time, and THA component during the first 2 years postoperatively in combi nation with radiographic findings of loosening should be considered a serio us predictive sign for loosening of a Mueller or Zweymueller THA component.